Foldable cranes

ABSTRACT

A crane comprising a foldable jib hinged to the upper end of a post which is in turn pivotally connected at its lower end to a rotatable base. Both the jib and the post are arranged to be angularly displaced by means of a common piston and cylinder assembly.

[111 3,819,059 ['45] June 25, 1974 United States Patent [191 Mantel [56] References Cited UNITED STATES PATENTS FOLDABLE CRANES [75] Inventor: Robert Mantel, Johannesburg, South Africa Assignee: Mantel Brothers (Proprietary) 2,198,793 4/1940 Schroeder.............,........... 212/59 R 3,047,160 7/1962 212/59 R Limited, Honeydew, South Africa Primary Examiner-Richard A. Schacher Assistant Examiner-Hadd S. Lane 0r FirmCushman, Darby ,&

2 7 9 l 6 6 6 mm D3 0 N .ml 0. mo. FA NH 22 [30] Foreign Application Priority Data Sept. 29,'l972 2247839 [57] ABSTRACT A crane comprising a foldable jib hinged to the upper end of a post which is in turn pivotally connected at its South 72/369 Jan. 19, 1972 U-Sa Cl- R, R lower end to a rotatable base Both the and the Int. Cl. post are arranged to be angularly disp]aced means 212/59, 58 R, 35 R, 35 HC,

[58] Field of Search.....

of a common piston and cylinder assembly.

9 Claims, 3 Drawing Figures PATENTEB M SHEET 1 {IF 2 F OLDABLE CRANES This invention relates to foldable cranes and more particularly, but not necessarily, to cranes adapted to be mounted on a truck and which may be folded to occupy a minimum space when not in use.

According to this invention there is provided a crane comprising a foldable jib hinged to the upper end of a post, the lower end of the post being pivotally connected to a rotatable base, both the hinged jib and pivotally connected post being adapted to be angularly displaced by means of a common piston and cylinder assembly.

Further features of the invention provide for the rotatable base to be a pillar mounted in a sleeve, for said assembly to be pivotally secured at one end to the pillar and at the other end to the jib, for stop means to be provided for limiting movement of the post between a folded and an erect position and for locking means to be provided for locking the post in an erect position.

A preferred embodiment of the invention is described below by way of example, reference being made to the accompanying schematic drawings, in which:

FIG. 1 is a side elevation of a foldable crane in a folded position;

FIG. 2 is a side elevation of part of the crane locked in an erected position; and

FIG. 3 is an end elevation of the part of the crane shown in FIG. 2.

In this embodiment of the invention an hydraulically controlled crane is adapted to be mounted on a truck chassis directly behind the cab and to be used in loading and unloading the truck.

The crane includes a rigid base 1 carrying a support member 2 rotatable relative to the base 1 about a vertical axis. In this embodiment of the invention the base 1 is provided with an upwardly projecting sleeve 3 wherein a pillar 4 is received, the support member 2 being secured to the upper end of the pillar.

The support member 2 is U-shaped in cross-section and has a post 5 hinged to the flanges thereof as indicated by numeral 6. The hinge 6 is positioned at the upper end of the support member andoff the-centre line of the pillar 4 towards a jib 7 of the crane. The post 5 comprises two parallel spaced plates 8, one extending from the outer major surface of each flange of the support member 2 and transverse brace plates 9 secured to the edges of the plates 8 along most of their length.

A piston and cylinder assembly 10 extends from a pivotal connection 11 on the jib 7 to a pivotal connection 12 on the support member, said connection 12 being located in the same horizontal plane as the hinge 6 of the post 5.

One end of the jib 7 is pivotally secured at 31 to the upper end of the post 5. A member is slidably fitted in the jib from the other end thereof. This member is telescopically extensible and retractable relative to the jib by means of an hydraulic ram located inside the jib. An arm 13 is pivotally secured to the free end of said member 15 and is operable through another piston and cylinder assembly in known manner. 3

The jib 7 and post 5 have co-operating surfaces 16 which ensure that the jib is horizontally disposed when the crane is in the folded position. It will be readily appreciated that the piston and cylinder assembly 10 prevents further downward movement of the post 5 when said assembly is in its retracted position. However, this retracted position need not correspond to the folded position of the post because stop means are provided as will be described below.

In use, and from the folded position, the arm 13 of the jib is firstly extended as is usual in this type of equipment. With this operation it will be understood that the centre of gravity of the crane will thus also shift in the direction of the arm 13 and consequently a moment tending to erect the crane will be provided about the hinge 6. However, movement is prohibited by the piston and cylinder assembly 10. Upon expansion of the latter, both the jib 7 and the post 5 will simultaneously rotate to the erected position.

Means are provided for automatically locking the post 5 in an erect position, said means being designed for automatic release as well. The locking means comprise two identical locking members 18 pivotally mounted on the post and adapted to prevent movement of the post from an erect to a folded position. The locking means co-operate with stop means adapted to prevent forward movement of the post from the erect position.

A pin 17 is secured transversely between the plates 8 of the post 5. It is secured adjacent the lower end of the post and is located such that it will be clear of the support member flange edges 26 remote from the hinge 6 when the post moves between the folded and erect positions. A locking member 18 is pivotally secured to each plate 8 of the post 5 adjacent the inner major surface thereof and in the same vertical plane as the corresponding flange of the support member 2, the pivoted connection 20 between each locking member and plate 8 being situated vertically above the pin 17. The lockingmembers 18 may conveniently be secured to a common shaft 21 extending transversely between the plates 8 and pivotally secured thereto.

Each locking member is provided with a recess formed in one side thereof and shaped to accommodate the pin 17 which acts as a stop to locate the locking members in a position where movement of the post from an erect to a folded position is prevented by virtue of engagement between each upper edge 19 of the support member and the edge 22 of each locking member remote from the pivoted connection 20. This position is shown in FIGS. 2 and 3.

Each locking member is provided with a co-planar lobe 23 at the upper end of the locking member and extending transversely to the general longitudinal axis thereof. The two locking members are connected to one another by means of a rod 24 extending between said lobes 23 and secured thereto. Two hollow bars 25 are pivotally secured to the rod 24, one on each side of the piston and cylinder assembly 10. The bars 25 are disposed in parallel, spaced relationship and extend from the rod 24 to the upper part of the post 5. Each bar projects a short distance through an aperture in the edge of the post defining the surface 16 thereof when the post is in an erect position with the jib spaced therefrom, as shown in FIG. 2. Each bar 25 is spring loaded in any convenient manner in an upward direction, thereby biasing the locking members towards contact with the pin 17.

Stop means are provided to limit movement of the post between a folded and an erect position. As shown, the pin 17 is pivotally connected to a guide pin 27 in parallel spaced relationship by means of two spaced carrier members 30. The guide pin extends transversely between the flanges of the support member 2 and is guided for movement in a slot 28 formed in each flange of the support member. When the guide pin 27 abuts the upper end of the slots 28, the post 5 is vertically disposed and forward movement of the post is prohibited. When the guide pin abuts the lower end of the slots 28, the post 5 is in the folded position. Although the post cannot rotate beyond the folded position in view of the different radii of rotation between the pin. 17, the hinge 6 and the guide pin 27, a stop (not shown) is preferably provided on the support member 2 to engage the lower edge of the post 5 when the latter is in the folded position. Said stop will thus prevent downward movement of the post from its folded position, thus preventing undue strain being placed on the pins 17, 27.

To release the post 5 from its vertical, locked position, the jib 7 is lowered until the co-operating surfaces 16 abut one another. This movement depresses the bars 25 and the two locking members are simultaneously pivoted out of contact with the upper edges 19 of the support member 2 as shown by the dotted lines 29 in FIG. 2. It will be appreciated that when the jib 7 is lowered, the centre of gravity of the crane will shift in the direction of the arm 13 of the jib and a moment tending to lift the post 5 off its locking members will be provided about the hinge 6. This movement takes the weight off the locking members and facilitates their pivoting out of contact with the-edges 19.

Upon further contraction of the piston and cylinder assembly 10, the post 5 rotates to the folded position, the lower portion of each locking member riding along its respective flange edge 26. When the post is raised as described above, the locking members ride along said edges 26 until they clear the upper edges of the flanges of the support member and snap into position against the pin 17. This position of the post corresponds to the uppermost position of the guide pin 27 in its slots 28 and the post is thus locked in an upright position.

It will be appreciated that at no time will the post 5 move forwardly'or rearwardly under the weight of the crane assembly only, as movement of the post is prohibited by the piston and cylinder assembly 10. Locking of the post in a vertical position is merely to prevent movement of the post from an erect position when the jib 7 is raised or lowered.

From the above it will be appreciated that the angularly collapsed position of the post 5 enables the crane to be folded so as to extend a minimum height above the cab, while also giving added height and reach to the crane when all the components are in the operative and extended condition.

The invention provides a collapsible crane assembly for use over an arc of 360 and which also gives a compact collapsed condition relative to the extended condition of the crane.

What I claim as new and desire to secure by Letters Patent is:

l. A crane, comprising:

a support member adapted for rotation about a vertical axis;

a post;

means pivoting the lower end of the post to the support member along a horizontal axis;

a jib;

means pivoting the one end of the jib to the upper end of the post about a horizontal axis; a piston and cylinder assembly having one member thereof pivotally secured and positioned to act against the support member and having the other member thereof pivotally secured and positioned to act against the jib; means for locking the post in an erect position, said locking means including: i at least one locking member, means pivoting the locking member on the post, stop means provided on the support member for engagement by the locking member when the post is erected, to prevent angular movement of the post from an erect toward a folded position so long as the locking member and stop means remain engaged,

means biasing one of the locking member and stop means toward locking engagement; and

bar means, positioned on the crane to be engaged by the jib as the jib is folded, to dislodge one of the locking member and stop means from locking engagement.

2. The crane of claim 1, wherein:

the support member includes at least one upright flange;

the post includes at least one flange generally parallel to corresponding flange of the support member;

the means pivoting the locking member on the post comprises a pin extending transversely of the flange of the post;

the at least one locking member includes a hookshaped plate disposed to hang from the pin and have a perimetrical portion thereof in sliding engagement with the flange of the support member;

other end of the slot when the post is fully erected;

the hook-shaped plate of the guide member including a recess which opens in a sense to receive the other pin as the erecting post drags the hook-shaped plate toward the other pin, whereupon the hookshaped plate, below the other pin, becomes pinched between the other pin and the flange of the support member to positively prevent folding of the post with respect to the support member.

3. The crane of claim 2, including further pin means connecting the bar means to the hook shaped plate at an off-set from the firstmentioned pin, so that as the jib engages the bar means, the bar means acts on the further pin in a sense to rotate the hook-shaped plate about the first-mentioned pin in a sense to withdraw the recess of the hook-shaped plate from about said other pin, thus also dislodging the hook-shaped plate below said other pin from between said other pin and the flange of the support member.

ton and cylinder assembly being pivotally secured to the same one end of jib about a fourth horizontal axis and positioned to act against the jib;

the post, when the piston and cylinder assembly is retracted extending upwardly at an inclination to vertical with the jib doubling back with respect thereto;

the first, second, third and fourth axes being positioned as follows:

so that an imaginary straight line directly proceeding transversally between the first and second axes crosses an imaginary straight line directly proceed- 6 ing transversally between the third and fourth axes, among these four axes, with the following result: that when the piston and cylinder assembly is in a retracted condition, the jib exerts a force on the post which tends to rotate the post toward an erect, more vertical condition, so that as the piston and cylinder assembly is being extended, said force tends to assist the piston and cylinder assembly with erection of the post I 5. A crane as claimed in claim 4 in which the base is a pillar mounted in a sleeve.

6. A crane as claimed in claim 4 in which the jib is telescopically extensible and has an arm pivoted at its free end about a horizontal axis.

7. A crane as claimed in claim 4 including a locking member pivoted to the post about a horizontal axis and adapted to engage the base to prevent movement of the post from the said vertical to inclined positions.

8. A crane as claimed in claim 7 in which the locking member is biased towards an engaged position and is displacable from this engaged position by means of a member projecting from the post and displacable by means of the jib.

9. The crane of claim 4 wherein the base includes a motor vehicle, whereby the crane is mobile. 

1. A crane, comprising: a support member adapted for rotation about a vertical axis; a post; means pivoting the lower end of the post to the support member along a horizontal axis; a jib; means pivoting the one end of the jib to the upper end of the post about a horizontal axis; a piston and cylinder assembly having one member thereof pivotally secured and positioned to act against the support member and having the other member thereof pivotally secured and positioned to act against the jib; means for locking the post in an erect position, said locking means including: at least one locking member, means pivoting the locking member on the post, stop means provided on the support member for engagement by the locking member when the post is erected, to prevent angular movement of the post from an erect toward a folded position so long as the locking member and stop means remain engaged, means biasing one of the locking member and stop means toward locking engagement; and bar means, positioned on the crane to be engaged by the jib as the jib is folded, to dislodge one of the locking member and stop means from locking engagement.
 2. The crane of claim 1, wherein: the support member includes at least one upright flange; the post includes at least one flange generally parallel to corresponding flange of the support member; the means pivoting the locking member on the post comprises a pin extending transversely of the flange of the post; the at leaSt one locking member includes a hook-shaped plate disposed to hang from the pin and have a perimetrical portion thereof in sliding engagement with the flange of the support member; the stop means including: means defining a slot transversely through the plate of the support member; a guide pin extending transversely in the slot; another pin, extending transversely of the flange of the post vertically below the first-mentioned pin; means connecting the other pin to the guide pin; the slot being of such length and such orientation that the guide pin engages one end thereof when the post is fully folded and the guide pin engages the other end of the slot when the post is fully erected; the hook-shaped plate of the guide member including a recess which opens in a sense to receive the other pin as the erecting post drags the hook-shaped plate toward the other pin, whereupon the hook-shaped plate, below the other pin, becomes pinched between the other pin and the flange of the support member to positively prevent folding of the post with respect to the support member.
 3. The crane of claim 2, including further pin means connecting the bar means to the hook-shaped plate at an off-set from the first-mentioned pin, so that as the jib engages the bar means, the bar means acts on the further pin in a sense to rotate the hook-shaped plate about the first-mentioned pin in a sense to withdraw the recess of the hook-shaped plate from about said other pin, thus also dislodging the hook-shaped plate below said other pin from between said other pin and the flange of the support member.
 4. A crane, comprising: a base; a support member mounted on said base for rotation about a vertical axis; a post; means pivoting the lower end of the post to the support along a first horizontal axis; a jib; means pivoting one end of the jib to the upper end of the post about a second horizontal axis; a piston and cylinder assembly having one member pivotally secured to the support member about a third horizontal axis and positioned to act against the support member; the other member of said piston and cylinder assembly being pivotally secured to the same one end of jib about a fourth horizontal axis and positioned to act against the jib; the post, when the piston and cylinder assembly is retracted extending upwardly at an inclination to vertical with the jib doubling back with respect thereto; the first, second, third and fourth axes being positioned as follows: so that an imaginary straight line directly proceeding transversally between the first and second axes crosses an imaginary straight line directly proceeding transversally between the third and fourth axes, among these four axes, with the following result: that when the piston and cylinder assembly is in a retracted condition, the jib exerts a force on the post which tends to rotate the post toward an erect, more vertical condition, so that as the piston and cylinder assembly is being extended, said force tends to assist the piston and cylinder assembly with erection of the post.
 5. A crane as claimed in claim 4 in which the base is a pillar mounted in a sleeve.
 6. A crane as claimed in claim 4 in which the jib is telescopically extensible and has an arm pivoted at its free end about a horizontal axis.
 7. A crane as claimed in claim 4 including a locking member pivoted to the post about a horizontal axis and adapted to engage the base to prevent movement of the post from the said vertical to inclined positions.
 8. A crane as claimed in claim 7 in which the locking member is biased towards an engaged position and is displacable from this engaged position by means of a member projecting from the post and displacable by means of the jib.
 9. The crane of claim 4 wherein the base includes a motor vehicle, whereby the crane is mobile. 